As a semiconductor material, a compound semiconductor, such as a silicon carbide four-layer period hexagonal crystal (4H-SiC), is publicly known. When fabricating a power semiconductor device using 4H-SiC as a semiconductor material, a SiC single crystal substrate is fabricated by epitaxially growing a 4H-SiC single crystal film (hereafter referred to as a SiC epitaxial film) on a semiconductor substrate made of 4H-SiC (hereafter referred to as a 4H-SiC substrate). Heretofore, as an epitaxial growth method, a chemical vapor deposition (CVD) method is publicly known.
Specifically, a SiC single crystal substrate on which is stacked a SiC epitaxial film formed by a chemical vapor deposition method is fabricated by thermally decomposing source gas, caused to flow into a reacting furnace (chamber), in carrier gas, and continuously depositing silicon (Si) atoms along with the crystal lattice of a 4H-SiC substrate. In general, as the source gas, monosilane (SiH4) gas and dimethylmethane (C3H8) gas are used, and as the carrier gas, hydrogen (H2) gas is used. Also, as doping gas, nitrogen (N2) gas or trimethylaluminum (TMA) gas is appropriately added.
In general, an epitaxial film, having a growth rate of on the order of several μm/h, cannot be grown at a high rate. Consequently, it takes significant time to grow an epitaxial film of a thickness of 100 μm or more required for fabricating a high voltage device, and an increase in epitaxial growth rate is required in terms of industrial production. As a method of growing an epitaxial film at a high rate, a halide CVD method using halide is publicly known. It is proposed that growth at a high rate of on the order of 100 μm/h is possible by a halide CVD method whereby monosilane gas and dimethylmethane gas acting as source gas, and gas containing chloride (Cl) such as hydrogen chloride gas (HCl) acting as additive gas are simultaneously introduced into a reacting furnace to grow a SiC epitaxial film (for example, refer to the following non-patent literature 1).